Method of producing metallic cesium



April 2, 1929. R. E. MIESSE 'METHO D OF PRODUCING METALLIC CESIUM Filed Jan. 1927 awwe'ntoz M4 ,9. M w

Patented Apr. 2', 1929.

RICHARD E. MIESSE, OF JERSEY CITY, NEW JERSEY, ASSIGNOR TO NEW PROCESS METALS CORPORATION, OF NEWARK,

JERSEY.

NEW JERSEY, A CORPORATION OF NEW METHOD OF PRODUCING METALLIC CESIUM.

Application filed January 3, 1927. Serial No. 158,581.

My invention relates to improvements in methods of producing metallic. caesium. The metal caesium is a particularly active chemical which reacts rapidly with oxygen and other elements and compounds and so is extremely unstable in the air and various other mediums, For these and other reasons it has been practically impossible to produce caesium in metal form on a commercial scale, although it has been known as a scientific fact that caesium could be produced in metallic form by reduction of a salt of caesium.

I have found that metallic caesium may be produced by reducing the same with a reducing agent in an ordinary vacuum, 1. e. 111 a vessel more or less evacuated or exhausted by a vacuum pump, but I have further discovered that the results obtained are quite unsatisfactory unless one or more of various conditions or features are employed in the process. In order to enable those skilled in the art to fully understand and carry out my invention and make use of my improvements I will describe a preferred method embodying the same. In carrying out the invention to produce metallic caesium in relatively large masses, I prefer to use an apparatus substantially like that shownin the accompanying drawing which forms a part of this specification. The drawing is a section through the apparatus.

Referring to thevdrawing, 1 represents a suitable tube or vessel preferably made of glass capable of withstanding the high temperatures to which it is to be subjected. The glass tube 1 is provided with a neck 2 having a plurality of constructions as at 3, 3. The

' neck 2 is adapted to be connected to a suitable vacuum pump so that the tube or vessel may be suitably exhausted thereby. At its bottom there is connected to the tube 1 by a restricted neck portion 4, a bulb 5. A suitable supporting means 6 of glass or suitable metal is provided for supporting a porcelain crucible 7 in the tube 1. Arranged in the crucible 7 is a coil of molybdenum wire 8, the terminals of which extend through the walls ofthe tube 1 at 9 and 10. The bulb 5 may be provided with suitable graduations at 11 for indicating the quantity of material in the bulb in grams or other units. The apparatus is hermetically sealed to the outside except through the exhaust neck 2 to which the vacuum pump is connected.

In operation, I preferably proceed as follows. I first place in the crucible 7 a suitable quantity of a mixture of caesium chloride and a rare earth metal alloy, preferably an alloy known as miseh metal, and comprising mainly cerium with some lanthanum and small quantities of other rare earth metals. This alloy may also preferably contain small quantities of iron, alumi num and other metals as Well as traces of oxides and/or nitrides of one or more of the metals. That is, the alloy may contain any one or more of the rare earth metals, together with one or more other metals such as iron, aluminum, lanthanum, etc.; or any one of the rare earth metals such as cerium, or lanthanum may be used alone as the reducing agent, although I prefer one of the alloys which is pyrophoricl The mixture of the caesium chloride and this reducing agent is pref rably introduced into the crucible 7 in pow ered form and placed therein so that the coil 8 will be embedded therein.

I then connect a suitable vacuum pump to the neck 2and exhaust the tube 1 and bulb 5 of gasesand continue the exhaustion until the tube 1 and bulb 5 have been evacuated toless than .001 millimeter of mercury. During the latter part of exhaustion the tube and bulb are heated in any well known or suitable manner to a temperature of about 270 C. or above to remove occluded gases from surfaces inside the bulb. After the vessel 1 with the bulb 5 have been thus evacuated and prepared, the mixture in the crucible 7 is heated by passing an alternating or direct current through the coil 8 by connecting the terminals of the coil to a suitable source of current. For this purpose I prefer to use a low potential current and of such value that the mixture in the crucible 7 is heated to a temperature suflicient to caus the caesium saltto be substantially re duced to metallic caesium. The metallic caesium so produced is given off from the crucible in the form of a vapor and is condensed. on cooling and flows down into the bulb 5 where it is collected, and the amount thus produced and collected is indicated by the graduations 11. When the desired amount of metallic caesium has thus been produced and collected in the bulb 5, the bulb 5 may be sealed off at 4 and separated from the tube 1 and the caesium kept in the bulb 5 until desired for use.

\Vhile I prefer to start with caesium chloride, other caesium salts may be used as a base from which to produce the metallic caesium. Various other changes may also be made in the process. If it is desired to use the metallic caesium in radio or other evacuated tubes or the like, the metallic caesium may be conveniently produced by the above process directly in the bulb or Vessel in which the metallic caesium is to be used.

Thus while I have described my improvements in detail and with respect to a pre ferred embodiment thereof. I do not desire to be limited to such details or form, since many changes and modifications may be made and the invention embodied in widely different forms without departing from the spirit and scope thereof in its broader aspects. Hence I desire to cover all modifications and forms coming within the language or scope of any one or more of the appended claims.

lVhat I claim as new and desire to secure by Letters Patent, is:

1. The method of producing metallic caesium which consists in placing a mixture of caesium chloride and a rare earth metal alloy reducing agent in a closed glass vessel, evacuating the vessel to less than .001 millimeter of mercury, heat-ing the vessel to about 270 C. or above, while the vessel is being exhausted to remove occluded gases from surfaces inside the "essel and finally heating the mixture of caesium salt and metallic reducing agent in the so evacuated vessel by means of an electric current to a temperature to cause the caesium salt to be substantially reduced to metallic caesium.

2. The method of producing metallic caesium which consists in placing a mixture of a caesium salt and a misch metal reducing agent in a closed glass vessel, evacuating the vessel and finally heating the mixture of caesium salt and metallic reducing agent in the so evacuated vessel to a temperature to cause the caesium salt to be substantially reduced to metallic caesium.

3. The method of producing metallic caesium which consists in placing a mixture of a caesium salt and a rare earth metal alloy reducing agent in a' closed glass vessel, evacuating the vessel, heating the vessel while the vessel is being exhausted to remove oceluded gases from surfaces inside the vessel and finally heating the mixture of caesium salt and metallic reducing agent in the so evacuated vessel by means of an electric current to a temperature to cause the caesium salt to be substantially reduced to metallic caesium.

4. The method of producing metallic caesium which consists in placing a mixture of a caesium salt and a rare earth metal alloy reducing agent in a closed glass vessel, evacuating the vessel, heating the vessel while the vessel is being exhausted to remove 00; eluded gases from surfaces inside the vessel and finally heating the mixture of caesium salt and metallic reducing agent in the so evacuated vessel to a temperature to cause the caesium salt to be substantially reduced to metallic caesium.

5. The method of producing metallic caesium which consists in placing a mixture of a caesium salt and a rare earth metal alloy reducing agent in a closed glass vessel, evacuating the vessel, heating the vessel while the vessel is being-exhausted to remove occluded gases from surfaces inside the vessel and finally heating the mixture of caesium salt and metallic reducing agent in the so evacuated vessel by means of an alternating current to a temperature to cause the caesium salt to be substantially reduced to metallic caesium.

6. The method of producing metallic caesium which consists in placing a mixture of a cmsium salt and a rare earth metal alloy reducing agent in a closed glass vessel, evacuating the vessel and finally heating the mixture of caesium salt and metallic reducing agent in the so evacuated vessel to a temperature to cause the caesium salt to be substantially reduced to metallic caesium.

7. The method of producing metallic caesium Which consists in placing a mixture of a caesium salt and a rare earth metal reducing agent in a closed vessel, evacuating thevessel and finally heating the mixture of caesium salt and rare earth metal reducing agent in the so evacuated vessel to a temperature to cause the caesium salt to be substantially reduced to metallic caesium.

8. The method of producing metallic caesium which consists in placing a caesium salt mixed with a rare earth metal reducing agent in a suitable chamber, evacuating the chamber to less than .001 millimeter of mercury, heating the chamber while it is be ing exhausted to remove occluded gases from surfaces inside the container, and finally heating the mixture of caesium salt and metallic reducing agent in the so evacuated chamber until caesium salt has been substantially reduced to metallic caesium.

9. The method of producing metallic caesium which consists in placing a mixture of caesium chloride and a rare earth metal reducing agent in aclosed glass vessel, evacuating the vessel to less than .001 millimeter of mercury, heating the vesselto about 27 0 C. or above, while the vessel is being exhausted to remove occluded gases from surfaces inside the vessel and finally heating the mixture of caesium salt and metallic reducing agent 'in the so evacuated vessel by means of an electric current to a temperature to cause the caesium salt to be substantially reduced to metallic caesium.

10. The method of producing metallic caesium which consists in placing a mixture of a caesium salt and a metallic reducing agent comprising an alloy of a rare earth metal in a closed glass vessel, evacuating the vessel, heating the vessel while the vessel is being exhausted to remove occluded gases from surfaces inside the vessel and finally heating the mixture of caesium salt and metallic reducing agent in the so evacuated vessel to a temperature to cause the caesium salt to be substantially reduced to metallic caesium. y

In testimony whereof I have signed my name to this specification.

RICHARD E. MIESSE. 

